The long range objective of this project is to understand at the molecular level how proteins are synthesized in mammals and how the process of protein synthesis is controlled at the levels of translation and transcription. The topics of current interest are: 1) the isolation and characterization of biologically active messenger RNA from early and term human placentas and from human cancer cells in culture, 2) the translation of eukaryotic mRNA in cell-free systems from wheat germ and Krebs ascites cells. 3) the identification and purification of immunoprecipitable forms of the human placental polypeptide hormones, human placental lactogen (hPL) and human chorionic gonadotropin (hCG) synthesized in cell-free systems, 4) the conversion in cell-free systems of possible precursors of hPL and hCG to mature hormones, 5) the examination of proteins resembling hPL and hCG synthesized in cell-free systems for biological activity.